Hi, I have no feeling in my vagina, it's numb. What could have caused this? I have been like this my whole life and it is causing a strain on my relationship. Is there anything I can do like a nerve grafting surgery or something ? Any advice would be greatly appreciated.

Have you tried anal? It takes a little getting used to, but you can orgasm that way. Some women even have more intense anal orgasm than vaginal.
This can be a problem if your boyfriend is very large, though.

Is the nerve grafting something your doctor has told you after a complete exam of the problems? Have you had STD or infections that has caused damages ?

No, no nerve grafting!
You are just guessing, right?
A lot of intercourse is purely mental, and the rest might be for you a lot of touching all over your body and all around your vagina, outside, inside, sideways, exploring to find out where your nerves are, for pity's sake. You need a partner who is willing to do more than just go for the finale.